Tubular getter container



NOV- 3, 1953 n c. F. vEENEMANs ETA; 2,657,452

TUBULAR GETTER CONTAINER Filed May 27, 1948 2 Sheets- Sheet 1 PNVENTORScomm/s f/rfafe//r MIMI/75M' Nbv.3,1953

Filed May 27, 194e c. F. vEENEMANs T Al. 2,657,452

TUBULAR GETTER CONTAINER 2 Sheets-Sheet 2 M 1Mr I l I' IMI Patented Nov.3, 195,3

TUBULAR GETTER CONTAINER Cornelis Frederik Veenemans, Simon HenricusRudolf Visser, and Frans Jansen, Eindhoven, Netherlands, assignors toHartford National Bank and Trust Company, Hartford, Conn., as

trustee Application May 27, 1948, Serial No. 29,558 Claims priority,application Netherlands October 27, 1947 4 Claims. (Cl. 29-25.13)

The invention relates to a tubular getter container comprising alongitudinal apertureV for volatillization of the getter and to ahigh-vacuum vessel, more particularly an electric discharge tube,provided with such a container. The term getter is to be understood tomean a gas absorbing substance.

In high-vacuum vessels general use is made of a gas-absorbing substance,ususally barium, which during and after its volatilization absorbs gasresidues left in the vacuum vessel. However, since many getters cannotbe exposed to air Without being attacked, they are frequently introducedinto the vacuum vessel within a container shaped into the form of aniron tube, this tube being severed from a long tube iilled with thegetter, for example barium, and welded to a nickel plate. When thenickel plate, and hence the tube, is being heated in the vacuum vesselthe getter evolves at the ends.

Such a container, however, has a disadvantage in that cutting the tubeto length must be effected a short time before its introduction into thevacuum vessel, since air is liable to enter through the open ends andbring about slowly proceeding oxidation of the barium, the barium oxideformed often becoming located loosely in the vacuum vessel.

In order to obviate this disadvantage and to enable the getter-iilledcontainers which have been cut to length to be stored in air for anylength of time the use of an alloy with aluminium instead of pure gettermetal, for example alkaline earth metal, has been contemplated. However,in this case another disadvantage persists in that during the severingoperation the ends of the tube are materially narrowed and when weldingonto a metal plate or strap the passage for the gas-absorbing metalcontained in the tube between the ends may be narrowed or choked.

In a further embodiment of frequent use in which a tube of metal, say,iron is filled with a barium-aluminium alloy and subsequently swaged anddrawn out into a wire having an external diameter of, for example, `0.8mm. and comprising a core of the said alloy 0.5 mm. in diameter, thedisadvantages outlined are obviated by grinding 01T the wall of the ironenvelope at one area in the direction of length so as to enable thebarium to evolve readily during the heating operation. The wire is thencut into lengths of about l cm. after small straps have been weldedthereto and this permits of heating by high-frequency currents.

The constructions here discussed have a disadvantage in that the issuingjet of vapour exhibits a wide spread, so that the barium vapour isliable to precipitate on a large part of the wall of the vacuum vesseland also on members, such as electrodes, present in this vessel. This isoften undesirable in view oi insulation and electrode capacities.

In order to give the jet of Vapour a denite direction, so that only asmall predetermined part of the wall of the vacuum vessel or of anelectrode may be covered with a getter mirror, vari- .ous forms ofgetter container have already been suggested. Thus, for example, it hasbeen proposed to use a box-shaped getter container provided with a smallspout which is kept cool, the getter vapour being thus enabled to issuein a thin jet. However, such a construction is comparatively complicatedand unsuited for mass production.

According to the invention, the use of a tubular getter containerpermits of providing a directional jet of getter vapour in a very simplemanner in that with such a getter container, in which the activesubstance when Volatilized is permitted to escape through a longitudinalaperture in the envelope, this aperture is shaped into the form of anarrow slit or slot, through which the getter vapour issues in the formof a directional jet. This may be effected in various ways. One methodstarts with a, say, iron or nickel envelope shaped into the form of atube the external diameter of which is approximately 8 mms. and the wallthickness 1.5 mm., a saw-cut about l mm. in Width being provided in thewall in the direction of length. Next, the tube is swaged in a rotaryrswaging machine or otherwise manipulated so as to close the saw-cut andthen lled with an alloy of barium and aluminium and subsequently drawnout to an external diameter of.

for example, 0.8 mm., the initial saw-cut beingy found to be againpresent in the shape of a narrow slit in the iron envelope. Although thewall thickness of the envelope is only about 0.15 mm. the emanatingvapour jet on volatilization of the getter, is found to be directed bythe side walls of the slit.

In accordance with a further, very suitable method the iron cylinder isnot previously provided with a saw-cut, but directly lled with an alloyof the getter substance and then swaged and drawn out to a diameter of,for example, 0.8 mm. The getter wire is then passed over a guide wheelabove which is arranged a cutting Wheel or a cutter having a V-shapedcutting profile which presses or cuts a V-shaped slo-t into theenvelope. The getter wire has then Welded on to it; vat =deinitegspacings;A small U-,shapedr straps in a given position relative to theslot, theI Wire being then cut between these straps.

In order that the invention may be more., clearly understood and readilycarried into effect, it will now be described more fullyewithqrefen enceto the accompanying drawingt in Awhich Fig. 1 is a sectional view of1ja,lnown. tubular., getter container,

Figs. 2 and 3 are sectionalviews ofatubnlarL getter containers accordingto the invention,

Fig. 4 is an elevation of suchAV a container 1p;A

mounted on a strap, and

Fig. 5 shows an electric high-vacuumvessel*- provided with such a gettercontainer.

Referring to the gures, l designates thegiron;` envelope, 2 the coreconstituted by gas-absorbing 20 substance..` .According toa known..embodiment the` envelope. l shown .in..-Figf.f 1 Yisground. so. .as to,-be-partlyzflat,,almostas far as theactive core.-

The.; vapours... of. thev active substance l.tweak thrugll thefthin..part :of ,the envelope and spread practicallysoverganangle, of 180.?,soy thatthe` vpulzlextends ,over .alarge area, which. ,is ,irequentlyundesirable.

The; iron. tube.A shown :in Fig. 2 wasinitiallyDrvdedfwitha.sawfcutandaafter the saw-.cut

had;.been c1osed by, swagng it was nlled with active substance and drawnout. it isuneXnect-,- edlyiound .that subsequent yto thedrawing:operation mesntiaagam. present. eine@ this sut isncircumscribed bysubstantially parallel ,wall-s, thee jet of x vapounescapes a ,sharplydennen direction... A* jet. of. vapour establos. from.4 the gettercontainer Shawmut-Fig. exhibits aslie" I 1y., wider. spread.. After,beingdrawn outl i Q a..` wire of the desired diameter this gettercontainer hastayeshaped slot .E-pressed or cut. into. its envelope.'firewire-shaped ,getter container khas thenrweldedto it` short, U:Shaped `Straps .6 for examplaof nickel. about `1 Graeme-in widthAandassevered between tnestraps.. As shown .in Fig, .4,the-getter.containerwith .the strap forrng-iI a, loopwhich. .rendershighly effective heating of thefgeytter.:bvhighffrequency currents.

. The. straps..provdedwith a getter container; are housed in vacuumvessels, particularly` in electric .-dischargef tubes, suchl that the?slit or f, slot occupiesfthe:desired-position. As snowmanthe. use ioffa:getter-, container accor ing to the, nventionfensures -thefgetterzpreipitates f onzafvery-li.. ited-,a-rea ofthe-tube wait; In the,caseeof ssma'll-jsized-:ltubes 1, this is f vel'yydesirable in .view .lof insulation fand.; electrode capacities,, Referring tosFig.. 5,thegetter container litorgether :with the straprx lissecured tof a -staypole afgetterwmirrorf is formed -ionly at azsmall':area` 65- off-fthe.tube walll Thev electrode L system` I0 is;-` consequently'fnot '-struck:bywthe getter` vapour.:-

and the electrode capacities are practically not affected owing to thesmall size of the getter mirror.

What weclaimwis:

l; A methpd of -manufacturing a'tubular getter container having atubular shaped metal envelope partially surrounding the said getter andfrom which envelope volatilized getter may escape inffafdirectional jet,comprising the steps of forming a longitudinal aperture in a Wall of atubular. metal-envelope, closing the said aperture. llingthetsogclosedenvelope with a pulverulent'gettersubstance, and drawing the soilledenvelopefito reduce the diameter thereof and to ,cause the said envelopeto separate along the ling ,of "the said longitudinal aperture.

2;Af`method of manufacturing a tubular getter container having a tubularshaped metal envelope-partially surrounding the said getter and fromwhich envelope volatilized getter may escapa in--a, ,directional. jet,comprising.: the steps offfforming. :.a. longitudinal aperture. in,awallnf atubular metal envelope,v swaging the; envelope to close.the-,said aperture, nl ling the so..swaged, envelopewith-a pulverulentgetter substance, and

drawing the so-filled envelope to `reduce/the diameter thereof and tocause thepsaid envelope toA separatealonglthe. linel of thel`saidmlongitudinal aperture.

3.. AJrnethod lof manufacturinga .tubular getter container having atubular: shaped"metal),en -v velopepartially surrounding thesaidgetterand j fijomwhich envelope, volatilizedgetter mayz es-v capeinadirectionalijet, comprising the steps of` formingalongitudinalaperture. in a wall of a tubular metal envelope,y swagingthe Venvelope tov close the said aperture, filling thewsofswaged envelope with analloy of aluminum .anddallalineearthrnetal, anddrawingrthe so-lled envelope toL reduce the diameter thereof anelitocause the n saidy envelope toseparate alongthieline of -the saidlongitudinallaperture.

4. A method .of manufacturing a tubular getter container having atubular shaped vmetal envelope partially surrounding the said getter andfrorn which envelopevolatilized getter mayY escapein a` directional jet,comprisingthe steps off for-ming a longitudinal aperture about1-1nm.--in' widthginga wall of atubular envelope havinganexternaljdiameterof about S-"mms: andfa' wall thickness of aboutl.5"mm., swaging the lenvelope' to closethe 0said aperture,llingthe-so-swaged envelope with" an alloy of Aalurninurnvand barium,`and drawing the so-filled envelope toan external diameter of *about .8lmm.V `to'cause the said-em velopepto separate along the line of thesaidf longitudinalaperture;-

CORNELIS FREDERIK1'VEEl\llll\/.lAl\lSa- SIMON -HENRlCUS1 RUDOLF--V1SSER-FRANS" JANSEN References Cited in the ile of this patentAv UNITED;STATES "PATENTS

